Inexpensive wiring conduit idea

Howdy,

I've been thinking about how to run wires in an aluminum wing that is already
finished. I can fish something through the holes in the ribs, but I don't
want to just let a wire or cable lay on the raw edges of the rib holes.

I think that the CPVC hot water tubing from Home Depot might make an excellent
conduit. It is light weight, flexible enough to fish through the structure,
and so tough it is hard to cut with a knife. After fishing it through the
wing, and tying it down on the two ends, it would be really easy to pull wires
through at any time later.

I don't know what the fire rating of the stuff is. But I do know that CPVC
has a much higher working temperature than regular pvc. It is used for
electrical conduit in building construction.

What do you think?

thanks,
tom pettit

tom pettit wrote...

....
I think that the CPVC hot water tubing from Home Depot
might make an excellent conduit.
....
What do you think?

That's what I did. Fishing it through a completed
wing sounds like it might be unsupported if you're
passing it through lightening holes or something
large like that. Might flop around and wear against
the ribs. I installed mine during construction
through press-fit holes (where it will also wear
with vibration, I suppose). I sort of assume
that since it's for residential use it doesn't give
off nasty stuff if it burns, but since it's outside
the cockpit and in a place where, if it's burning,
I've got a lot more to worry about than fumes, I'm
not concerned if it does give of bad fumes.

Dave 'spaghetti' Hyde

RV-4 in flight test, EAA tech counselor

wrote in message
...
Howdy,

I've been thinking about how to run wires in an aluminum wing that is
already
finished. I can fish something through the holes in the ribs, but I don't
want to just let a wire or cable lay on the raw edges of the rib holes.

I think that the CPVC hot water tubing from Home Depot might make an
excellent
conduit. It is light weight, flexible enough to fish through the
structure,
and so tough it is hard to cut with a knife. After fishing it through the
wing, and tying it down on the two ends, it would be really easy to pull
wires
through at any time later.

I don't know what the fire rating of the stuff is. But I do know that
CPVC
has a much higher working temperature than regular pvc. It is used for
electrical conduit in building construction.

What do you think?

thanks,
tom pettit

The house electrical conduit is PVC. Also, just because it is in a house,
does NOT mean that it doesn't give off nasty fumes. You are free to leave a
house when it burns, but not so for an airplane.

Try this, instead. Take a piece of pipe, long enough for the run you are
going to do, and make it about 3/16" smaller in diameter than the holes in
the ribs. (or smaller)

Use brown paper (you can get it at wallyworld type places, in the shipping
supplies area) and cut a long strip, just wide enough to go around the pipe
one time. Tape it together, with small pieces of scotch tape, but not to
the pipe. Cut long strips of paper, a couple of inches wide, and wet them
out in a wood glue and water mixture. Wrap the pipe and paper, like a
toilet paper tube, with just a little overlap. Let it dry, and slide it off
the pipe, and install it.

It will burn, but not for long, since there is not much fuel in it. Added
bonus of not as much weight as the cpvc.

Let us know how it works. I did it all the time in giant scale RC planes.
--
Jim in NC

I've been thinking about how to run wires in an aluminum wing that is already

finished.

---------------------------------------

Dear Tom,

This will sound a little hokey but it worked surprisingly well.

The 'wire' was in fact a piece of mini-coax with two stranded leads bundled
within an outer braided metal sheath. The wire was fixed to the area of the
new antenna/inspecition plate then secured to the ribs & bulkheads through
which it passed with blobs of an RTV compound applied via an piece of tubing 8'
long. The work went pretty quick, the fun part being the chorus-line of
inspectors, each for a particular aspect of the job, who bobbed & weaved their
way around each other to peek through their mirrors & telescopes as first the
wire was fished then the RTV elastomere was applied.
(O&R facility, NAS North Island, about 1973)

-R.S.Hoover

PS - Working inside a closed structure, be it wing, spar or whatever, is
usually called 'mouse work.' In fact, the buck for riviting under those
conditions is still called a mouse. The term supposedly stems from using a pet
mouse or rat to carry a thread the length of a DC-2 outer wing panel. Douglas
plant, early 1930's. The mouse story was still being told when my dad went to
work at El Segundo in 1937 but by then they had a whole array of blow-guns to
shoot a pilot line through a closed structure.

On Sat, 28 Aug 2004 17:53:07 GMT, wrote:

Howdy,

I've been thinking about how to run wires in an aluminum wing that is already
finished. I can fish something through the holes in the ribs, but I don't
want to just let a wire or cable lay on the raw edges of the rib holes.

One idea I read years ago was to use thin mylar sheet. Roll it tightly
into a tube, slip it through the holes, then turn it loose. It'll uncoil
until it makes contact with the edges of the holes, then run your wires
through it.

Ron Wanttaja

wrote in message ...
Howdy,

I've been thinking about how to run wires in an aluminum wing that is already
finished. I can fish something through the holes in the ribs, but I don't
want to just let a wire or cable lay on the raw edges of the rib holes.

tom pettit

How big is the wire? Does it really need to go inside the wing?
Sometimes there is room in the flap/aileron bay in which to tuck the
wire. If it does have to go through the wing there have been some
imaginative thought already posted. I like the Kraft paper tube idea
but might sub something that isn't hydrophilic - like the mylar.
=========================
Leon McAtee
Spent a wonderfull day sorting out SGU 2-22 parts and getting all
covered in micro dust sanding my canard. More of the same in the AM

Ron Wanttaja wrote:
On Sat, 28 Aug 2004 17:53:07 GMT, wrote:


Howdy,

I've been thinking about how to run wires in an aluminum wing that is already
finished. I can fish something through the holes in the ribs, but I don't
want to just let a wire or cable lay on the raw edges of the rib holes.


One idea I read years ago was to use thin mylar sheet. Roll it tightly
into a tube, slip it through the holes, then turn it loose. It'll uncoil
until it makes contact with the edges of the holes, then run your wires
through it.

Ron Wanttaja
I like it; can you get it in long enough sheets (at an affordable price)
to reach at least from tip to inspection plate and inspection plate to root?

My plan so far has been to try the same technique using thin AL flashing
material from Home Depot a/c supply, but this sounds just as light
without the risk of cutting the wire on the AL.

Charlie

On Sun, 29 Aug 2004 10:05:01 -0500, Charlie England
wrote:

One idea I read years ago was to use thin mylar sheet. Roll it tightly
into a tube, slip it through the holes, then turn it loose. It'll uncoil
until it makes contact with the edges of the holes, then run your wires
through it.

Ron Wanttaja
I like it; can you get it in long enough sheets (at an affordable price)
to reach at least from tip to inspection plate and inspection plate to root?

My plan so far has been to try the same technique using thin AL flashing
material from Home Depot a/c supply, but this sounds just as light
without the risk of cutting the wire on the AL.

We used to buy it in rolls for drafting from any blueprint supply
place, from 0.002" to 0.007" thick. This was, however, 30 years ago
before CAD. A quick Google search shows it to still be avaialble.

3M and Mitsbishi Polyester Film both make TONS (no exageration g) of
this stuff without the matte finish, but I don't know who their
custoemrs are.

(PS; Mylar is duPont's trademark for polyester film)

"Charlie England" wrote in message
. ..
Ron Wanttaja wrote:
On Sat, 28 Aug 2004 17:53:07 GMT, wrote:


Howdy,

I've been thinking about how to run wires in an aluminum wing that is
already
finished. I can fish something through the holes in the ribs, but I
don't
want to just let a wire or cable lay on the raw edges of the rib holes.


One idea I read years ago was to use thin mylar sheet. Roll it tightly
into a tube, slip it through the holes, then turn it loose. It'll uncoil
until it makes contact with the edges of the holes, then run your wires
through it.

Ron Wanttaja
I like it; can you get it in long enough sheets (at an affordable price)
to reach at least from tip to inspection plate and inspection plate to
root?

My plan so far has been to try the same technique using thin AL flashing
material from Home Depot a/c supply, but this sounds just as light
without the risk of cutting the wire on the AL.

Charlie

McMaster-Carr has polyester (generic for Mylar) film in rolls up to 25 feet.

You might also consider Tyvek -- which is a non-woven (paper-like) sheet
made of polyester.
It's used as vapor barrier in housing, but I don't know if it would be stiff
enough.

Tim Ward

"Tim Ward" wrote

You might also consider Tyvek -- which is a non-woven (paper-like) sheet
made of polyester.
It's used as vapor barrier in housing, but I don't know if it would be
stiff
enough.

Tim Ward

No, not stiff enough.

Jim (the house building contractor) in NC